Hydraulic Workover Unit Dynamic Sealing for Live Well Operations
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Solution Overview
Problem
In hydrocarbon production, overbalanced wells require artificial lift, and during live well workovers, the presence of gases like hydrogen sulfide poses challenges for traditional blowout preventers, which struggle to seal around irregularly shaped ESP production strings, necessitating a solution for safe and effective pressure containment and movement of equipment.
Innovation Solution
A hydraulic workover system with a combination of static and dynamic blowout preventers, including a reciprocating riser and elastomeric sealing elements, allows for the safe insertion and removal of ESP completions without killing the well, using a telescoping assembly for dynamic sealing and pressure control during snubbing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional blowout preventers are used with conventional drill pipe methods, then well pressure control is achieved, but the ability to seal around irregularly shaped ESP production strings is insufficient
Solution Approach 1:
The patent employs flexible elastomeric sealing elements within the blowout preventer assembly that can conform to irregularly shaped ESP production strings. These elastomeric elements deform to match the contour of the tubing string, creating an effective seal around non-circular or irregular geometries while maintaining well pressure control.
Solution Approach 2:
The blowout preventer system utilizes changeable sealing elements that can be adjusted or replaced to accommodate different tubing string configurations. The elastomeric materials can change their physical parameters such as hardness and flexibility to adapt to various production string shapes and sizes, enabling reliable sealing across different well conditions.
2Reliability
If kill weight fluids are used to control well pressure, then pressure control is achieved, but formation damage occurs in overbalanced wells
Solution Approach 1:
The patent eliminates the need for kill weight fluids by implementing a mechanical sealing system through the blowout preventer assembly. By extracting the fluid-based pressure control method and replacing it with a mechanical seal, the system achieves pressure control without introducing harmful fluids that could damage the formation in overbalanced wells.
Solution Approach 2:
The blowout preventer assembly acts as an intermediary mechanism between the wellbore and the workover equipment. It provides a physical barrier that contains well pressure through mechanical sealing rather than chemical or fluid-based methods, thereby preventing formation damage while maintaining pressure control during live well workovers.
3Object-affected harmful factors
If live well workover is performed without kill fluids, then formation damage is prevented, but the ability to contain gas and maintain pressure integrity becomes challenging
Solution Approach 1:
The elastomeric sealing elements in the blowout preventer provide flexible, conforming seals that effectively contain gas and maintain pressure integrity during live well workovers. These flexible materials adapt to the tubing string shape and create reliable barriers against gas migration, enabling safe workover operations without kill fluids.
Solution Approach 2:
The blowout preventer assembly utilizes composite construction combining rigid structural components with flexible elastomeric sealing materials. This composite approach provides both the structural strength needed for pressure containment and the flexibility required to seal around irregularly shaped production strings, achieving reliable pressure integrity during live well operations.
4Reliability
If conventional drill pipe methods are used, then well pressure control is achieved, but the complexity of making up and breaking up pipe sections increases operational time
Solution Approach 1:
The blowout preventer assembly serves multiple functions simultaneously: it provides pressure containment, seals around irregularly shaped tubing, and enables the telescoping mechanism to move equipment in and out of the well. This multi-functionality eliminates the need for separate operations of making up and breaking up conventional drill pipe sections, significantly reducing operational time while maintaining pressure control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables safe and efficient live well workovers by maintaining well pressure integrity, preventing formation damage, and reducing operational costs by eliminating the need for kill fluids, while effectively managing gas presence and irregularly shaped tubing.
Implementation Method 1
a second dynamic blowout preventer mounted on the other portion. The first static blow out preventer has a tubular riser attached thereto, which tubular riser extends through and is sealingly engaged by the second dynamic blow out preventer
Data Source
AI summary
A workover unit for lowering an irregularly shaped production string into a live well includes a traveling assembly and stationary assembly movable relative to each other. The traveling assembly may include a traveling static annular BOP configured to seal around the production string during the lowering. The traveling assembly may include a reciprocating riser connected to the traveling annular BOP. The traveling assembly may include traveling slips configured to grip the production string during the lowering. The stationary assembly may include a dynamic BOP configured to seal around the reciprocating riser during the lowering. The stationary assembly may include a reciprocating jack configured to lower the traveling assembly. The stationary assembly may include a lower static annular BOP configured to seal around the production string when the traveling assembly is moved relative to the production string.